GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Lucerne 🢒 DTC 🢒 DTC B2545

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B2545 00: Backup Lamps Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

B+, BCM C4 Terminal 4

B2545 00

B2545 00

--

--

Backup Lamps Voltage Supply

B2545 00

1

2

--

  1. Backup Lamps Inoperative
  2. Backup Lamps Always On

Circuit/System Description

When the PRNDL is placed in the REVERSE position, a signal is sent to the body control module (BCM). The BCM then applies voltage through the backup lamps voltage supply circuit to the left and right backup lamps.

Conditions for Running the DTC

The ignition is ON. The backup lamps must be commanded ON.

Conditions for Setting the DTC

The BCM detects a short to ground on the backup lamps supply voltage circuit.

Action Taken When the DTC Sets

The BCM will deactivate the backup lamps for the remainder of the ignition cycle.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

Ignition ON, place the PRNDL to the REVERSE position. The backup lamps should illuminate.

Circuit/System Testing
  1. Ignition OFF, disconnect the (C4) harness connector at the BCM.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.
    3. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the backup lamp supply voltage circuit terminal 2 (C6) for a short to ground.
  3. Ignition OFF, disconnect the harness connectors at the components listed below.
    4. • Inside rearview mirror
    • Left tail lamp assembly
    • Right tail lamp assembly
  4. Connect a test lamp between the left backup lamp supply voltage circuit terminal 1 and ground.
  5. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    6. ⇒If the test lamp is always ON, test the supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.
    ⇒If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Clear the DTC with a scan tool.
  7. Reconnect each component one at a time and operate the system under the Conditions for Running the DTC. Verify the DTC does not reset as current.
    8. ⇒If the DTC resets as current, test or replace the component responsible for setting the DTC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Tail Lamp Replacement
    •  Inside Rearview Mirror Replacement
    •  Control Module References for BCM replacement, setup, and programming